The present invention relates to a guiding apparatus comprising a base and being a slider and guided by a hydrostatic bearing and, more particularly, to a guiding apparatus capable of performing an absolute positioning of the slider with respect to an intended coordinate position.
This type of guiding apparatus is used when a highly precise positioning is required as in the case of assembling of photo module elements or mounting of electronic parts on a printed board.
Hitherto, a hydrostatic guiding apparatus has been used as the means of precise positioning. This hydrostatic guiding apparatus has hydrostatic bearings for supporting the slider in a floating manner above the base, thereby ensuring low friction and high rigidity. An example of such a hydrostatic guiding apparatus is shown, for example, in the paper of symposium of the Academy of Precision Machine, spring in 1982, pp 204-206.
In this type of guiding apparatus, the slider floats relative to the base and moves along the base so that the absolute precision of positioning is determined finally by the precision of machining of the base.
The hydrostatic guiding means of this guiding apparatus is generally comprises two parallel guide surfaces presented by the base and an opposing inner surface of the slider. Therefore, the precision of positioning is largely affected not only by the precision of machining of the guide surfaces but also by the precision of assembling of the base and the slider having such guide surfaces.
The precision of positioning is affected also by a distortion or a displacement of the movable part including the slider during the driving of the slider along the base.